-LRB- CNN -RRB- -- The International Atomic Energy Agency issued a critical report Tuesday saying that it has `` serious concerns '' about Iran 's nuclear program and has obtained `` credible '' information that the Islamic republic may be developing nuclear weapons .

The IAEA report , the most detailed to date on the Iranian program 's military scope , found no evidence that Iran has made a strategic decision to actually build a bomb . But its nuclear program is more ambitious and structured , and more progress has been made than previously known .

`` The agency has serious concerns regarding possible military dimensions to Iran 's nuclear program , '' the report said . `` After assessing carefully and critically the extensive information available to it , the agency finds the information to be , overall , credible . The information indicates that Iran has carried out activities relevant to the development of a nuclear explosive device . ''

U.S. State Department spokeswoman Victoria Nuland said the report had just arrived and refrained from commenting on details at an afternoon briefing . But a senior U.S. official called the report `` a big deal . ''

`` The report is very comprehensive , credible , quite damning , and alarming , '' the official said .

Read the IAEA report here

Iranian President Mahmoud Ahmadinejad slammed the report as a fabrication of facts aimed at satisfying U.S. allegations about Iran 's nuclear program .

Ahmadinejad essentially called Yukiya Amano , the director general of the IAEA , a U.S. puppet and said the United Nations agency has no jurisdiction in Iran .

`` The Americans have fabricated a stack of papers and he keeps speaking about them , '' he said on state-run Press TV . `` Why do n't you do a report on the U.S. nuclear program and its allies ? Present a report on the thousands of U.S. military bases where Washington has nuclear arms that threaten global security . ''

The IAEA had released another report on Iran in September but this one was highly anticipated because of the military aspect .

Since 2002 , the IAEA has regularly received new information pertaining to the development of a nuclear payload for a missile , the report said .

It said Iran has made `` efforts , some successful , to procure nuclear related and dual use equipment and materials by military related individuals and entities '' and has acquired nuclear weapons information from `` a clandestine nuclear supply network . ''

It has also worked on mastering the design of a nuclear weapon and tested components , the report said .

The IAEA said the some of the activities have both civilian and military applications , but others are specific to nuclear weapons .

Iran has repeatedly insisted its nuclear program is for peaceful , civilian energy purposes only .

According to the IAEA report , Iran is believed to have continued weapons research and technology development after 2003 , when the intelligence community thought Iran had stopped . Instead of halting , it seems Iran took a temporary hiatus at the time , although the program progressed at a more modest pace since then , the report said .

After the report 's release , top Republicans in Congress called on President Barack Obama 's administration to ratchet up economic sanctions against Iran . Rep. Mike Rogers , the chairman of the House Intelligence Committee , raised the fear that Israel would attack Iranian nuclear facilities without further steps by the United States and its allies .

Rogers , R-Michigan , said new sanctions should cut off the supply of refined fuel to Iran and target its central bank , which he said is being used to finance Tehran 's nuclear program .

`` If we talk about it for a long time , if we 're not really leading on it , I will tell you we leave this option to the Israelis , '' he told CNN 's `` John King USA . ''

And in a written statement , Rep. Ileana Ros-Lehtinen called on Congress to pass two bills targeting Iran 's energy sector . The Florida Republican leads the House Foreign Affairs Committee , which recently sent legislation to the House floor to do just that .

`` If fully implemented , they have the potential to cripple the regime 's ability to continue its nuclear program , '' she said . `` If the Iranian regime acquires nuclear weapons capabilities , the U.S. , Israel and our other allies in the region and around the world will face an unimaginable threat to our security . The clock is ticking . ''

Previous IAEA reports have cited concerns by the organization that Iran has been seeking to develop nuclear warheads and ballistic missiles to deliver them .

Word of the latest report drew strong comments in Israel , where talks of how to deal with Iran have recently hit fever pitch . Israel considers Iran its arch-nemesis for its repeated innuendos about the destruction of the Jewish state .

Ahead of the report 's release , Israeli Defense Minister Ehud Barak warned that his nation would consider every option in countering Iran 's bomb-making capabilities .

`` Israel does not want a confrontation , but if it happens , the state of Israel will not be destroyed and there will not be 10,000 dead and not even 500 dead in any possible scenario , '' Barak said Tuesday on Israel Radio .

Iranian Defense Minister Brig. Gen. Ahmad Vahidi said Iranian armed forces were in `` full combat readiness and will give a crushing response to those daring to attack the country , '' IRNA said .

The United States , Vahidi said , was trying to `` promote Iranophobia '' in a bid to attain its `` sinister goals . ''

Western powers have long suspected that Iran 's nuclear program is geared toward weapons development . The United States is looking to increase the heat on Iran , including a possible strengthening of existing sanctions on Iran 's financial and banking sectors and additional political pressure -- all of which could be applied by the United States alone or in coordination with other allies .

The United States also hopes international organizations , such as the United Nations , will take steps to further isolate Iran diplomatically .

Officials said that one of several options being considered is sanctioning the Central Bank of Iran , although the United States is mindful of the impact such a move could have on oil prices during a time of global economic turmoil .

U.S. officials said the Obama administration will use the report to lobby the international community to slap new economic sanctions against Iran .

Obama said he discussed the upcoming report with French President Nicolas Sarkozy in Cannes , France , during a meeting of the G-20 industrialized nations . The U.S. president said the two leaders `` agreed on the need to maintain the unprecedented international pressure on Iran to meet its obligations . ''

CNN 's Elise Labott , Jill Dougherty and Moni Basu contributed to this report .

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NEW : GOP members of Congress urge White House to ratchet up economic sanctions

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NEW : Sanctions should target refined fuel supply , Iran 's central bank , Rep. Mike Rogers says

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A nuclear watchdog report expresses serious concern over Iran 's nuclear program

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Iranian President Mahmoud Ahmadinejad dismisses the report as fabrication